The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Pumps for fluids encompass a broad range of mechanical configurations and flow characteristics. One frequent pump flow design requirement is constant or non-pulsating flow. This requirement generally eliminates piston pumps which typically have one or more reciprocating pistons producing a pulsating flow and pressure output. Centrifugal pumps provide a significantly smoother output flow but exhibit performance characteristics that vary widely with speed.
Gerotor and gear pumps represent a middle ground between the foregoing conflicting performance criteria. On the one hand, their construction, which includes two rotating and meshing members, provides a relatively smooth, i.e., non-pulsating, output. On the other, since the pump is essentially a positive displacement type, its speed versus flow and pressure characteristics are essentially proportional. Accordingly, gerotor and gear pumps find wide use in applications requiring a straightforward design, extended service life, minimal pulsation and predictable flow characteristics.
Occasionally, an issue arises with gerotor and gear pumps with regard to sealing between the meshing members and its influence on through flow. i.e., forward and especially reverse flow, when the pump is not operating. Aside from negligible flow between the side and end surfaces of the members and the stationary housing, the most significant flow occurs between the meshing or nearly meshing members. Depending upon the positions of the members and, more specifically, the extent to which any reverse (or forward) flow and pressure is capable of back driving the pump members, there may be an opportunity for relatively significant backward or forward flow through the non-operating pump. Such flow through a non-operating pump is generally undesirable especially in parallel pump installations or installations where air may be drawn through the non-operating pump into the suction side of the operating pump.